High level speaker out to sub

[Jamus]

I'm interested in adding a sub to my stereo setup which is a Kaiju into Klipsch Fortes. I grabbed one of my Hsu STF-2s from HT duty to try it out. The sub has high level speaker inputs that I'd like to connect to the kaiju speaker outs. However, the Hsu manual mentions that the black speaker outs on your amp have to be "true ground". Is that the case with Kaiju?

[Doc B.]

We are going to have to guess what "true ground" means. My hunch would be they mean the cold leg of the output is tied to signal ground. That is not the case with the Kaiju, which has a balanced output, i.e. both legs of the output have 60.4 ohms impedance relative to ground. You can modify the configuration to be grounded. Remove the 60.4 ohm resistor that goes from the red post to ground, and replace the 60.4 ohm resistor that goes from the black post to ground with a wire jumper. That will ground the cold (black post) leg of the output.

[Jamus]

Thanks Doc, I'm not sure this will be a permanent change, just experimenting at this point. Do most other subs have this requirement or is this specific to the Hsu amp? Any sub you can recommend that plays nice with the Kaiju?

[Doc B.]

It would probably make more sense to ask Shu how they wire their amps than me, as I am not at all familiar with them. I would suggest that a line level input on the subwoofer amp, with a separate level control, makes more sense technically than driving a subwoofer amp with the main speaker amp thru speaker level inputs.

[Jamus]

I spoke with Hsu's tech support. As I understand it, if the black leads aren't grounded in the stereo amp they will short to each other when hooked up at the sub's high level inputs.  Unfortunately there is no line level input on this sub. Could the BeePre be used to send a signal to the sub in this case?

[Doc B.]

I am surprised that there is only a speaker level input. The BeePre is a line level device and does not put out a speaker level signal, so that is not going to work well. But rewiring the speaker output of the Kaiju as I suggest will give only a very small penalty in the bass performance. I find the balanced wiring to give a little better bass control, but that is subjective. That penalty could, in theory, be compensated for by the use of the sub. That would be the easiest way to make the setup work.

[Jamus]

Thanks for the help, Doc!